Hello and Thank You for using Just Answer. You are not alone in dealing with your son throwing up when he gets upset and cannot have his way. Many parents go through the same thing. If you have taken him to the doctor for a routine check up and discussed the situation with the doctor and there are no underlying medical conditions, then your son will be fine. Although as frustrating as it may be for you, your son has a sensitive gag reflex. It is more of a matter of anxiety as well. The best thing you can do when he is starting to gag is to remain calm, do not negatively discipline him which will only make the situation worse, get down to his eye level and tell him to calm himself down in a soothing manner. Tell him that you will help him and listen to him when he settles down. Patience and consistency is the key. As a side note, if he goes to pre-school or daycare, he may have witnessed other children doing the throwing up routine as an attention getting mechanism. But when he does throw up, have him help you clean up the mess. He will get tired of doing that real fast.
Have a wonderful day!!!!